At the end of 2009, the 3D movie “Avatar” topped the box office in over 30 countries around the world, to early September 2010, the worldwide cumulative box office exceeds 2.7 billion US dollars. “Avatar” has been able to achieve such a brilliant performance at the box office, since it uses the new 3D effects production technologies to provide the shock effect to people's senses. Gorgeous graphics and realistic sound from “Avatar” not only shocked the audience, but also makes the industry have a assertion of “movie into the 3D era”. Not only that, it also spawned many more relevant video, recording, playback technologies and standards. In the International Consumer Electronics Show in January 2010 in Las Vegas, color TV giants had flaunted new TV which bring the people new expectations—3D has become a new focus of competition among the global major TV manufacturers. To achieve a better viewing experience, it needs 3D sound field hearing effect synchronized with the content of 3D video, in order to truly achieve an immersive audio-visual experience. Early 3D audio system (for example Ambisonics System), due to its complex structure, has high requirements for the capture and playback devices, and is difficult to be promoted. In recent years, NHK company in Japan launched a 22.2-channel system, which can reproduce the original 3D sound field through 24 speakers. In 2011, MPEG proceed to develop the international standard of the 3D audio, hopes to restore the 3D sound field through less speakers and headphones when reaching a certain coding efficiency, in order to promote the technology to the ordinary households. This shows the 3D audio and video technology has become research focus of the multimedia technology and important direction of further development.
However, the conventional 3D audio only focus on restoring the spatial location or a physical sound field of the sound source, and does not focus on restoring the size of the acoustic image of the sound source, especially the acoustic image body. In order to achieve better sound effect, it needs to restore the size of the acoustic image body accurately, and meanwhile in order to facilitate encoding and decoding and the other system processing, it also need to find the parameters representing sound source acoustic image body, then the original audio and video can be restored perfectly even after processed by the 3D audio system.